Determining vertical dimension and centric occulsion in denture construction



3,381,377 DETERMINING VERTICAL DIMENSION AND CENTRIC OCCLUSION May 7, 1968 w. o. GRAYSON IN DENTURE CONSTRUCTION Filed Jan. 11, 1965 INVENTOR.

' Mum/v 0. BY

United States Patent 3,381,377 DETERMINING VERTICAL DIMENSION AND CENTRIC OCCULSION IN DEN- TURE CONSTRUCTION William 0. Grayson, 3662 Cedars Ave.,

Mobile, Ala. 36603 Filed Jan. 11, 1965, Ser. No. 424,564 8 Claims. (or. 32-49 ABSTRACT OF THE DISCLOSURE Dental apparatus for determining the relative positions of the upper and lower jaws without interfering with normal movements of the jaws by inducing a voltage in one coil attached to one jaw by voltage applied to a second coil attached to the other jaw, the magnitude of the induced voltage being a function of the jaw separation. The coils can be mounted within the bite blocks used in constructing full dentures.

This invention relates to the practice of dentistry, and in greater particular of accurately locating the natural position of the lower jaw at rest and the position at centric occlusion.

While this invention has utility in determining relative positions of the upper and lower jaws in the mouth of a patient for reasons other than obtaining dimensions from which full dentures can be constructed, it is especially useful in the latter environment and this specification describes the invention with relation to obtaining dimensions for constructing full dentures, without limitations thereto being intended.

The natural or rest position of the lower jaw or mandible of a person is used in this application to refer to the position of the lower jaw when the masticatory muscles are at a physiological rest (resting tenus). Centric occlusion as used herein refers to the normal jaw relationship when upper and lower teeth are occluded.

It is imperative, for initial and continued comfort of the patient, from the physical, mental, speech, aesthetics and appearance standpoints, that his dentures be made in accordance with the most accurate normal dimensions that can be obtained, and it is therefore the principal object of this invention to provide an improved method and apparatus by which such accurate dimensions can be obtained.

In the past, rest position has been determined in various ways some of which require equipping a patient with exterior apparatus, such as a frame which rests on the nose bridge and ears and has apparatus extending down the nose and cooperating with the chin, or such as that which straps over the head or fastens to the base of the head, or such as face meters for measuring distance from various parts of the face. All such prior art equipment not only creates a distortion in the normal position of the lower jaw at rest, but is extremely uncomfortable to the patient during the time that the dimensions are being made. Accuracy and comfort are also questionable in the method of determining rest position by use of a patch-like piece stuck on the cheek under an eye extending downward toward the side of the chin.

It is therefore another object of this invention to provide an improved method and apparatus for determining the rest position and centric occlusion without requiring any external apparatus that aflixes to any part of the head of the patient.

Still another object of this invention is the provision of an improved method and apparatus for determining dimensions in the mouth of a dental patient by electrical means.

3,381,377 Patented May 7, 1968 Another object, in conjunction with the preceding object, is the provision of electrical distance-sensing elements positionable in the patients mouth, as in upper and lower bite blocks or the like, for providing, when energy supplied thereto is measured, an indication of the dimension sought.

Other objects and advantages of this invention will become apparent to those of ordinary skill in the art upon reading the appended claims and the following detailed disclosure in conjunction with the drawings, in which:

FIGURE 1 is a front elevational view with the patients face shown in phantom line,

FIGURE 2 is an enlarged fragmentary vertical section along line 22 of FIGURE 1,

FIGURE 3 is an exploded perspective view of a part of the equipment of FIGURE 1, and

FIGURE 4 is an electrical schematic diagram of a circuit constructed in accordance with principles of this invention.

It is to be understood that the phraseology and terminology herein employed is for purposes of description and not of limitation since the scope of the present invention is denoted by the appended claims. The present invention, in both its method and apparatus form, can best be explained by a general description of the technique of which the invention forms a part.

It may be assumed, as an example, that a dental technician in his laboratory, possibly remote from the office of the dentist, assists in the preparation and fabrication of dental plates in accordance with measurements and other instructions obtained and supplied to him by the dentist as a result of his examination of the patients mouth. On the other hand, the dentist himself may be operative in the physical preparation and fabrication of the dentures. An operative procedure of a dentist and his technician (or the dentist alone) may be as follows:

First, the dentist prepares a pair of upper and lower jaw impressions (not shown) in plaster or any other suitable material by standard procedure requiring neither illustration nor detailed description.

Second, the technician fabricates two stone or plaster models (not shown) from the two impressions, one for each jaw. These models are complementary to the upper and lower jaw impressions furnished by the dentist and simulate the upper jaw and palate and the lower jaw respectively of the patient. Base plate members are then made to conform the models. These base plate members may be made of any material suitable for the purpose, such as hardening plaster or a synthetic: plastic material, which may be heated, and formed to fit the models. Each is generally a thin-walled concave-convex member accurately conformed to fit the corresponding jaw model on its concave base and is curved smoothly on its convex base. Next, base plate wax or the like is softened and adjusted over the convex base or ridge areas of the upper and lower base plates. (As fully described below, this conventional procedure of building the formed plate up with wax, is not followed in the present invention as to one of the plates.) The wax on the upper base plate usually extends downward about 12 millimeters (mm.) from the peripheral border of the upper base plate, while the wax on the lower base plate is generally built up from the peripheral border about 10 mm. The resultant wax bite blocks or rims may then be used by the dentist to take the bite of the patients mouth. This information, along with various other dimensions and positions obtained are utilized by the dentist or technician in subsequent steps to complete the fabrication of a set of dental plates in conventional manner.

As above indicated, it is an object of the present invention to provide accurate information to the dentist and his technician concerning the relative vertical positions of the upper and lower jaws when they are in a rest position and also when they are in a position of a centric occlusion. In the practice of this invention, a conventional upper bite block 10, made for example as above described, has added to it, i.e. preferably imbedded in it, a distance sensing element which is specifically illustrated as an electrical coil 12. This coil is preferably secured to bite block before the block is placed in the oral cavity or mouth of the patient. For reasons that are more clear below, coil 12 is preferably disposed slightly to one side (the patients right side, as illustrated) of the median line 16, in the front portion of the block. The coil may be of two, three, or more turns as desired, wound flat, and mounted horizontally. Preferably also, coil 12 is flush with the lower surface of bite block 10.

While bite block 10 is generally of the conventional type with a base plate 18 on the ridge of which is built up a body of wax 20 in which coil 12 is imbedded, the lower bite block 22 is non-conventional in that it has no normal build up of wax or the like, but includes a conventional, formed base plate 24. In FIGURES l and 2, plate 24 has no build up of wax whatsoever, but instead it may be a conventionally built up block with the wax removed (or not originally applied) in the front area of the plate where, in any event, an occlusal stop and bearing plate device 26 is secured. This device has a bottom plate 28 (FIGURE 3) which is fixedly mounted to the front ridge area of base plate 24, as by luting with high fusing wax or modelling compound or the like, preferably in such a position that the set screw 30 is located on n the median line 16. As is apparent especially in FIGURE 3, set screw 30 threads through the wall of a tube 32 so as to secure therein a rod 34 at any desired height. As shown, rod 34 is scaled, for example with graduations in millimeters. To the upper end of rod 34 is secured a bearing plate 36, which may be made of clear plastic or the like. Initially, rod 34 is lowered all the way into tube 34, for reasons which become apparent below.

As indicated in FIGURES l and 2 the lower base plate has secured to it a second distance sensing element 38, which is also an electrical coil. This coil is mechanically secured to plate 24 in any desirable manner, for example by use of high fusing wax or modelling compound. Generally, the coil is physically and electrically similar to coil 12 in the upper bite block, though the number of its turns may be such as to step up (or down, if desired) the voltage induced in it by coil 12 when the latter is energized. Orientation of the turns of the coil is preferably the same as for coil 12 (horizontal) in order to obtain the best induction in coil 38. Preferably, coil 38 is aligned vertically with coil 12 so that it is on the same side (right) of median line 16 and is in the same forward-rearward position, as well as the same rightward-leftward position, as coil 12.

While coils 12 and 38 are indicated as being mounted adjacent the front of the upper and lower bite blocks, they may as well be mounted at any other region of the bite blocks, as desired. For example, in extreme cases of protrusion or retrusion, the coils might need to be placed in the molar regions of the bite blocks, but as will be appreciated upon attaining an understanding of this invention, such a placement would create no problem as all movements of the lower jaw could be registered in this position of the coils as efliciently as in the interior position. The off-center positioning of the coils as illustrated is because it is more desirable to have the occlusal stop device 26 centered on median line 16.

Because of the possibility of an abnormal protrusive or retrusive relationship of the lower jaw with respect to the upper jaw, it is preferable to secure coil 38 to the lower plate 24 after the plate is inserted over the lower gum of the patient. However, this invention also contemplates securing the coil 38 to plate 24 before the plate is inserted in the mouth, if such is desired,

Leads 40 of upper coil 12 and leads 42 of lower coil 38 in FIGURE 1 are connected, as illustrated in FIG- URE 4, respectively to coupling coils 44 and 46. Coil 44 is coupled to the tank coil 48 of an oscillator 50, which may be of the illustrated Hartley type, for example. The output of oscillator 50 is air coupled from coil 48 to coil 44, which is connected to coil 12 in the upper bite block. Oscillation energy thereby coupled to coil 12 is, in turn, transferred by air coupling or induction to the lower coil 38. The energy so induced in coil 38 is in turn conveyed by leads 42 to coil 46 in a remote receiver 52. Coil 46 air couples the energy into a tank circuit 54, which includes a variable inductance coil 56 and a condenser 58. This parallel LC circuit is tuned to the frequency of oscillator 50, so that the circuit is especially selective of the oscillation energy which has the frequency of oscillator 50. The output of tuned circuit 54 is amplified by an amplifying device, such as transistor 60, to which the signal is coupled via a diode rectifier 61, a smoothing condenser 62 and a sensitivity control rheostat 64. To the output of the collector terminal of transistor 68 is connected loading resistors 66, which are in series with a meter 68. A meter zeroing or control potentiometer 70 is connected across meter 68', with the tap thereof being connected to the negative side of battery 72. The positive terminal of this battery connects through a main switch 74 to the common line 76 of the oscillator and receiver circuits 50 and 52.

As above indicated, oscillator circuit 50 is illustrated as of the Hartley type, but of course it may be any other desired type of oscillator. In particular, oscillator 50 includes an amplifying transistor 78 the emitter of which is connected to the positive line 76. The base and collector electrodes of transistor '78 connect across tuning coil 48 with there being a bypass condenser 80 in the base line. Connected across a part of coil 48 to form therewith a parallel LC circuit is a condenser 82, which is further connected along with base resistor 84 to the negative terminal of battery 72. The circuit oscillates in conventional manner, and preferably is tuned to a frequency in the VHF range.

If desired the oscillator circuit 50 and receiver circuit 52 are contained in a housing or casing, shown diagrammatically by dash line 86. Of course the housing is disposed in a convenient location for the dentist, with leads 40 and 42 to the coils mounted in the patients mouth, being flexible. Meter 68 is preferably exhibited on the front of the housing, along with respective knobs (not shown) for controlling the variable taps of the sensitivity controlling potentiometer 64 and the meter zeroing potentiometer 70. Preferably meter 68 is of the center zero type.

In operation, after the bite blocks and their coils and the occlusal stop device of this invention are fully installed in the patients mouth and switch 74 is closed, oscillator 52 provides oscillations at a predetermined frequency to the upper coil 12 in the patients mouth, via the coupling coil 44 and leads 40. Corresponding oscillations are induced in the lower coil 38, in an amplitude dependent on the distance between coils 12 and 38-. Variation in the vertical dimension between coils 12 and 38 in the patients mouth, and therefore variation in the coefiicient of coupling between the coils, may be noted by a corresponding variation on meter 68. Lateral movements of the lower jaw also changes the separation distance between coils 12 and 38, and this change may likewise be noted by meter 68 as later noted, but first it is desired to determine the rest position using only vertical movements of the lower jaw.

Initially, bearing plate 36 is lowered to its fullest extent, so that the lower jaw may be moved without interference between the plate and the upper bite block 10. To obtain the rest position of the lower jaw, the dentist instructs the patient to say a series of certain words or phrases with rest times in between. The sensitivity of receiver 52 may be adjusted by variation of potentiometer 64, as necessary to cause meter 68 to respond in the desired response range. When the dentist notes the reading to which the meter always returns during the rest times, he may then elevate bearing plate 36 so that the upper bite block rests on the plate at the noted rest position reading of the meter. The graduations on rod 34 then supplies the dentist and his technician with the required rest position dimension to be used in a conventional manner to construct dentures. If desired, meter 68 may then he zeroed by operation of the arm of potentiometer 70 so that zero reading represents the located rest position. In this manner, the rest position can be readily returned to as the dentist desires.

To obtain centric occlusion, it is necessary to simulate the equipment to a teeth occluding position, rather than endeavor to determine a centric position with the jaws in a rest position. It is known that there exists a space (free way space) of from 2 to 4 mm. from rest position to centric occlusion. Bearing plate 36 can therefore be lowered to compensate for this space, using 3 mm. as the average, for example. The patient is then instructed to execute right and left lateral motions of his lower jaw, along with protrusive and retrusive movements and opening and closing movements, in the normal manner of seeking centric occlusion. With this invention, a consistent reading, i.e., a single reading which is frequently repeated relative position of the upper and lower jaws at this readduring such movements, is indicated by meter 68. The ing indicates centric occlusion. While being maintained in this position, the upper bite block and lower bite block or rim 22 are locked together in any suitable manner, as by introducing quick-setting plaster of paris, a softened low fusing wax or, preferably, one of the alginate impression materials, in the space between the bite blocks. After sufficient setting time, the locked bite blocks are removed from the patients mouth and attached in normal fashion to a conventional articulator for use in further preparation of the dentures, in well known manner.

As may be noted in FIGURE 4, the oscillator makes use of a transistor and a low voltage battery, whereby small, non-dangerous voltage and current are maintained. The oscillator coils 44 and 48 are preferably encased in plastic for insulation and leads 40 may be of the small, well insulated, hearing aid type. With such precautions, there is no danger of electrically shocking a patient.

While it has been above indicated that the source 50 for the energy which is supplied to the coil 12 in the mouth, is of the oscillator type, any other desired manner of supplying energy thereto may be employed, and such may naturally vary according to the type of distance sensing elements used in the mouth. These elements have been specifically illustrated as coils l2 and 38, but it is to be understood that other electrical and magnetic sensors may be employed in accordance with this invention. For example, this invention contemplates use of a distance sensing capacitor arrangement, or a variable inductance arrangement of the type in which the insertion distance of a core in a coil varies, or a linear variable differential transformer arrangement, or any other position transducer that can safely be used to provide an electrical output signal which varies proportionately to the distance between the sensors respectively mounted adjacent the upper and lower jaws. In any event variation in the coupling of the impedances involved, upon relative movement of the jaws, causes the proportional electrical output signal.

Further variations in the circuitry and equipment may be used as desired. It is of course apparent that the en ergized distance sensing element or coil 12 may be mounted on the lower base plate 24 with the other coil 38 mounted in the upper bite block 10, instead of the opposite arrangement illustrated and above discussed. In like manner, the occlusal stop and bearing plate device 26 may be mounted on an upper base plate instead of the lower one, if desired. While it has been indicated that the two coils 12 and 38 should be vertically aligned, this is not an absolute necessity as long as the distance therebetween changes automatically in proportion to changes in distance between the upper and lower jaws. It has been indicated that hearing plate 36 is lowered 3 mm. for we ample from the rest position to effect an occlusion position. This of course is accomplished by loosening set screw 30 and using the graduations of rod 34 to indicate the amount that the plate is being lowered. Instead of this arrangement, however, plate 36 may be made of two plates the upper one of which is removable and fits with the lower one in a respective tongue and groove relationship. The upper plate would then have a thickness of 3 mm. on the average, so that removal of the upper plate would allow the upper bite block to rest on the smooth surface of the lower plate and place the upper and lower jaws in an occlusion position.

It is therefore apparent that this invention has provided for all of the objects and advantages herein mentioned. Still other objects and advantages, and even further modifications and embodiments of this invention, will be come apparent to those of ordinary skill in the art upon reading this disclosure. However, it is to be understood that this disclosure is considered exemplary and not limitative, the invention being defined by the appended claims.

What is claimed is:

1. Dental apparatus for determining the rest position of the upper and lower jaws of a patient, comprising:

distance sensing means mountable wholly inside the oral cavity of said patient so as not to interfere with the normal movement of said jaws while determining a particular position thereof, including sensors mounted on respective base plates which are respectively mountable directly on the gums of said jaws for relative movement therewith, for providing an output signal varying as the distance between said sensors, and

means coupled to said distance sensing means for indicating from said varying output signal a normal predetermined position of said lower jaw.

2. Apparatus as in claim 1 wherein said predetermined position is the rest position and one of said base plates has secured to it a device having an adjustable height bearing means for resting the other of said base plates at a height differential less than for said rest position in order to obtain centric occlusion from said indicating means.

3. Apparatus as in claim 1 wherein said sensors are respective electrical coils, and said apparatus further includes an oscillator for supplying oscillations to one of said coils, and a receiving means connected to the other of said coils for detecting the amount of oscillation energy transferred from said one coil as a measure of the effective distance between said jaws.

4. Dental apparatus for determining a rest position of the lower jaw relative to the upper jaw in the mouth of a patient as an aid in constructing full dentures for the patient, comprising:

a bite block mountable on the jaw,

a first electrical coil imbedded in said bite block adjacent the front lower edge thereof,

a base plate mountable on the gum of the lower jaw of said patient,

a second electrical coil mounted on said base plate in substantial vertical alignment with said first electrical coil,

an oscillator circuit coupled to supply oscillation energy to one of said coils at a predetermined frequency,

a circuit tuned to said frequency and coupled to the other of said coils, and

an energy level detecting and indicating circuit, ineluding a meter, connected to said tuned circuit for measuring the amplitude of said oscillation energy gum of said upper induced by said one coil in the other coil as an indication of the separation distance therebetween.

5. Dental apparatus for determining the rest position and centric occlusion of the lower jaw relative to the upper jaw in the mouth of a patient as an aid in constructing full dentures for the patient, comprising:

a bit block mountable on the gum of said upper a first electrical coil imbedded in said bite block adjacent the front lower edge thereof to one side of the median line of the block,

a base plate mountable on the gum of the lower jaw of said patient,

an occlusal stop and bearing plate device secured to said base plate along the median line thereof,

said bearing plate being adjustable in height for supporting said bite block when desired,

a second electrical coil mounted on said base plate to said one side of the median line of said base plate in substantial vertical alignment with said first electrical coil,

an oscillator circuit coupled to supply oscillation energy to one of said coils at a predetermined frequency,

a circuit tuned to said frequency and coupled to the other of said coils, and

an energy level detecting and indicating circuit, in-

cluding a meter, connected to said tuned circuit for measuring the amplitude of said oscillation energy induced by said one coil in the other coil as an indication of the separation distance therebetween in a vertical sense for determining the rest position and in at least a horizontal sense for determining centric occlusion.

6. In the method of determining rest position during the process of constructing full dentures, the improvement comprising the steps of:

affixing a distance sensing element to a bite block,

inserting said bite block over one of the gums of a patient, inserting over the other gum a formed rim having mounted on it an adjustable height bearing plate,

afi lxing a second distance sensing element to said rim in substantial vertical alignment with said first electrical coil, connecting said elements to electrical circuit means, metering variations of electrical energy in said circuit means as caused by corresponding variations in distance between said sensing elements, and

indicating the bearing plate height found by said metering as corresponding to the rest position of said lower jaw.

'7. The method of claim 6 and including determining centric occlusion by the further steps of:

adjusting the height of said bearing plate to the desired vertical dimension for occlusion, and

locking said bite block and rim together at the metered indication of centric occlusion.

8. The method of claim 6 wherein the step of connecting said elements to electrical circuit means includes supplying electrical energy to one of said elements and detecting the energy thereby coupled to the other element, said metering being of the amount of detected energy.

References Cited UNITED STATES PATENTS 1,328,007 1/1920 Mannan 33148 2,265,775 6/1940 Dencz 340-213 2,411,194 11/1946 De Rome 32--19 2,827,041 3/1958 Pierson 128-2.1 3,153,282 10/1964 Brewer 32-19 3,259,984 7/1966 Seidenburg 3232 RICHARD A. GAUDET, Primary Examiner.

I. W. HINEY, Assistant Examiner. 

